Joint for furniture

ABSTRACT

A device for rigidly interconnecting wood panels or other parts of a piece of furniture. The joint comprises a finned shank and a head, secured within a seat provided in a first panel, and the head being removably engageable with a pin projecting from a second panel to be connected to the former. 
     The joint head comprises a seat coaxial with the shank, and open at the front and top for introducing the pin from above; on the bottom and at intermediate position, the seat in the joint head also has a transverse rib for engagement with a slot at the pin end. A closure cover clamps the pin in the seat and has projecting tabs for rotational engagement within longitudinal slots provided internally of the head at the top of the rib.

This invention relates to a plastic joint for furniture for mutual engagement and disengagement between panels and other parts of furniture to be assembled in situ.

The trend has been widespread among furniture manufactures to use joints or connection elements to allow for highest capability in furniture disassembling and reassembling. However, the joints or connection elements as hitherto used were not provided with all the necessary requirements from the standpoint of both usage thereof and complete mechanization of required operations for application thereof.

Particularly, if not impossible, it was often difficult with prior art joints to introduce and assemble furniture parts without knocking against or interferring with the structure or other assembled parts of the piece of furniture, such as it occurs when assembling the back or rear part of a piece of furniture.

Moreover, when presetting joints and anchoring pins in panels and/or assembling furniture parts, close working tolerances should be complied with, since a misalignment of the pin relative to its associated joint would prevent any assembling between elements. However, a substantial reduction in ranges or working tolerances is extremely difficult and involves the use of highly costly equipments. This is obviated by a particular embodiment of a joint according to the invention which allows to take up misalignments in the order of a few millimeters of the joint. Thus, the presetting operation for joint accomodating holes in considerably facilitated, without resorting to sophisticated and expensive equipments.

Generally, a joint for furniture according to the invention comprises a shank for fastening in a slot of a first panel or furniture part, as well as a head removably engageable with a pin projecting from a second panel or furniture part to be connected to the former, the joint head defining a seat coaxial with the shank and open at the front and top for introducing said pin from above; at the bottom and intermediate position said joint head having a transverse rib for engagement with the shape end of said pin; a pin clamping cover closing at the top said seat and having projecting tabs for rotational engagement in longitudinal slots provided in the side walls of said seat.

Furthermore, the spacing of the cover engaging slots from the bottom of said seat is the same as or slightly less than the pin diameter, so that the pin can be firmly clamped and retained in place by the cover.

These and further characteristics of a furniture joint according to the invention will be hereinafter shown in greater detail with reference to the accompanying drawings, in which:

FIG. 1 is a fragmentary sectional view of a joint according to the invention for the connection of two panels of a piece of furniture;

FIG. 2 is a top plan view showing the joint according to the invention with the cover applied thereto;

FIG. 3 is an exploded front view of a joint according to the invention;

FIG. 4 is a view similar to that of FIG. 2, but with omission of the cover;

FIG. 5 is a view showing the cover only, the view being taken in a plane orthogonal to that of FIG. 3; and

FIG. 6 is a cross-sectional view of the joint head, according to a further embodiment of the invention.

Referring now to FIGS. 1 through 5 of the accompanying drawings, a first embodiment of a furniture joint according to the invention will be hereinafter described.

As shown by the above figures, the joint is entirely moulded of plastic material and substantially comprises a shank 1 suitable for fastening within a hole of a first panel 3 of a piece of furniture, and also comprises a head 4 for removably engageing with a metal pin 5 projecting from a second panel 6 intended to be connected with the former. Similarly to join shank 1, said head 4 is inserted in a suitable slot 2 formed in the edge of said panel 3, as shown.

Shank 1 has a longitudinal slit, 7, wherein a wedge-like or spreading element 8 can be forced, so that the shank tabs or finnings 9 will penetrate into the wood and firmly anchor within said panel slot 2 by merely exerting an axial push on the joint. Of course, instead of the shank anchoring system shown in the accompanying drawings, any other joint anchoring system could be used.

As shown in the sectional view of FIG. 1, pin 5 projects from said second panel 6 by being secured to the latter, for example through a shank 5' which is threaded and screwed down in a hole suitably preset in the panel. Still as shown by the sectional view of FIG. 1, said pin 5 has its end suitably shaped with a head 5" joined by a neck or narrowed postion 10 defining a circumferential groove for engagement with said joint head 4, as explained in the following.

As shown in said figure, joint head 4 is of a substantially cylindrical shape, having its axis at right angles to the axis of shank 1. Thus, the joint can be merely accomodated within panel 3 by a first drilling operation for providing the slot or housing for shank 1, and a second drilling operation for providing the slot or housing for head 4. This head 4 also has two rigid side tabs 11 which can be penetrated and forced into the wood for an increased stability of the joint.

Joint head 4 has a seat 12 for pin 5, which seat is open at the front and top allowing the introduction of said pin 5 from above, or by a movement in a direction at right angles to the joint axis. Therefore, the upper aperture of seat 12 should have at least the same width or a larger width than the diameter of pin 5. The insertion of pin 5 from above, that is to say in a direction at right angles to the joint axis, is extremely advantageous as allowing to assemble elements of the piece of furniture without interfering with previously assembled parts or elements, such as occurring with the back or rear closure parts of furniture.

The engagement between said pin 5 and joint head is carried out through the cooperation of a rib 13 provided on the bottom of seat 12 and a top closure cover 14 which performs the function of clamping and holding pin 5, once the latter has been inserted.

Particularly, as shown by the sectional view of FIG. 1 and views of FIGS. 3 and 4, seat 12 of said joint head has at intermediate position on its bottom said rib 13 which, in the example shown, also partly extends on the sidewalls of the seat, defining an opening 13' for the passage of the pin neck 10, beyond which the head 5" of said pin is positioned. Therefore, pin head 5" is arranged between the bottom wall of seat 12 and 13 to be axially retained.

Clamping of pin 5 in seat 12 of the joint head occurs through the action of clamping cover 14. At an underlying position, this cover 14 has two projecting tabs 15 rotationally inserted in longitudinal slots 16 (FIG. 3) provided in the sidewalls of seat 12 at a position overlying said pin head retaining rib 13. As shown in FIGS. 3 and 5, these tabs 15 have a chamfered side edge promoting forced introduction of the tabs into joint head slots 16. The rotation of cover 14 is arrested by lugs or projections 14' abutting against ribs or ridges 17 provided at the top of the head.

Preferably, the spacing between the opposite ends of tabs is by about 0.3 or 0.4 mm larger than the spacing between the bottoms of longitudinal slots 16. Therefore, when cover 14 is rotated, said tabs 15 act upon head 4, forcing it to adhere against the walls in the panel seat. Thus, a substantial increase is provided in traction load required for casual or accidental withdrawal of the joint.

The longitudinal sectional view of FIG. 1 shows a further feature of a joint according to the invention. As a matter of fact, it is generally impossible to preset said joint and pin 5 initially at a correct axial position free of clearances. Therefore, the joint according to the invention has been designed to compensate for any axial clearances which might occur when inserting said pin 5 in the joint. Such a compensation is due to the action of inclined surfaces both on the surface of rib 13 facing the rear wall of the seat, that is to say facing said shank 1, and on the surface of pin head 5" facing said rib 13. As a result, the clamping action of cover 14 tending to force pin 5 in a direction at right angles to its axis is converted through the action of said inclined surfaces into a forward axial slide of the pin, thereby taking up the clearances that otherwise might exist between the edge of panel 3 and the opposing surface of panel 6. Thus, a rigid and firm connection between the two panels is provided.

The use of the joint shown in FIGS. 1 through 5 is substantially as follows: after drilling a first longitudinal hole 2 in panel 3 from the edge and a subsequent drilling operation in a direction at right angles to the previously drilled hole for accomodating both said shank 1 and joint head 4, the joint is inserted and clamped through a push action tending to cause wedge-like element 8 to penetrate into slit 7 of shank 1. Thus, said wedge-like element 8 causes the shank to radially expand, clamping it against the wall of hole 2. Additionally, said pin 5 is preset at proper position on panel 6. Now, after removing cover 14 from the joint head, by a movement of panel 6 and accordingly of pin 5 in a direction at right angles to the joint axis, said pin is introduced from above, positioning its head 5" beyond rib 13. Then, cover 14 is re-positioned with the tabs oriented parallel to seat 12, as shown in the exploded view of FIG. 3, the cover is inserted in said seat and rotated in clockwise direction, as seen in FIG. 2, until projections or lugs 14' abut against stops 17. Thus, the lower tabs 15 of the cover will penetrate into side slots 16, exerting a force on pin 5, which is thereby clamped in place. Disassembling of the parts may be carried out by inverting the above described operations.

In the example shown in FIGS. 1 through 5, seat 12 for accommodating pin 5 is of a width which, in a plane at right angles of the joint axis, substantially corresponds to or is slightly larger than the pin diameter. Therefore, the joint shown in FIG. 1 requires an accurate positioning relative to said pin 5 of panel 6, since the panels should be accurately positioned and as two or more points are generally simultaneously used, any misalignment between pins 5 and associated joints would render panel assembling impossible.

The foregoing can be obviated to, that is misalignments in the order of a few millimeters can be compensated for by the joint shown in the sectional view of FIG. 6. As a principle, this joint shown in FIG. 6 is substantially identical to that shown in FIGS. 1 through 5. The basic differences is that in this latter case the width of seat 12 for pin 5 is substantially larger, for example 1.5 times the width or diameter thereof. As a result, whichever is the position that pin 5 has with respect to seat 12', an interengagement is provided by the parts. Therefore, also in the case of FIG. 6, the joint is provided with a shank 1 and head 4, the seat of which is closed by a cover 14 quite identical to the former. A further differences with respect to the former joint is that head 4 has now a substantially cylindrical shape coaxial with shank 1. Therefore, the joint seat can be provided, for example, by a single operation, using a drilling or milling tool having two parts of different diameter.

Therefore, it is to be understood that the matter above described and shown in the accompanying drawings has been given by mere way of illustration of the solution concept as disclosed and mentioned in the appended claims. 

What I claim is:
 1. A joint for furniture, comprising a shank and head for fastening in an opening formed in a first panel, said head removably engaging with a pin projecting from a second panel to interconnect the first and second panels, said pin having a shaped head, wherein the joint head defines a seat coaxial with said shank, which seat is open at the front and top for the introduction of said pin from above; said seat in the joint head having longitudinal slots formed internally and a transverse rib extending from an intermediate portion of the bottom of said seat engageable with the shaped end of the pin; a clamping cover operatively associated with said seat for clamping the pin and for closing at top of said seat, said clamping cover having projecting tabs rotationally engageable in said longitudinal slots provided internally of said head.
 2. A joint according to claim 1, wherein the side of said rib facing said shank has an inclined surface cooperating with a corresponding inclined surface of the pin head to take up axial clearances.
 3. A joint according to claim 1, wherein the width of said seat substantially corresponds to the diameter of said pin.
 4. A joint according to claim 1, wherein the width of said seat is larger than the diameter of said pin.
 5. A joint according to claim 1, wherein the width of said projecting tabs of said clamping cover corresponds to the upper opening of said seat.
 6. A joint according to claim 1, wherein said projecting tabs of the cover have chamfered edges in the direction of rotation of said cover.
 7. A joint according to claim 1, wherein the spacing between the ends of said tabs is larger than the spacing between the bottoms of the slots in said head.
 8. A joint according to claim 1, wherein said joint head is a cylindrical shape with its axis at right angles to the longitudinal axis of said shank.
 9. A joint according to claim 1, wherein said joint head has a cylindrical configuration coaxial with the joint shank. 